IIC communication with STC51 microcontroller

[Tom Ming]

Hi @John Maloney

I have a remote control car, and its motor drive uses IIC communication, that is, I can control the motor through IIC communication with the STC51 microcontroller. There is a liberary for Arduino UNO communication. The liberary is as below:

/**
 * File: mecanumCar_v2.cpp
 * Function: Control source file for mecanum car v2
 * Suitable for raspberry pi pico
 * Author: Deng Fei
 * Date: 2022.7.4
 */

#include "MecanumCar_v2.h"
#include "Arduino.h"

uint8_t speed_Upper_L = 80;
uint8_t speed_Lower_L = 80;
uint8_t speed_Upper_R = 80;
uint8_t speed_Lower_R = 80;

mecanumCar::mecanumCar(int _sda, int _scl)
{
  SDA = _sda;
  SCL = _scl;
  pinMode(SDA, OUTPUT); //SDA总线为输出模式
  pinMode(SCL, OUTPUT); //SCL总线为输出模式
}

/* mecanumCar初始化函数
 */
void mecanumCar::Init() {
  delay(1000);
  right_led(0);
  left_led(0);
  Stop();
}


void mecanumCar::Stop() {
  Motor_Upper_L(0, 0);
  Motor_Lower_L(0, 0);
  Motor_Upper_R(0, 0);
  Motor_Lower_R(0, 0);
}


void mecanumCar::Advance()
{
  Motor_Upper_L(1, speed_Upper_L);
  Motor_Lower_L(1, speed_Lower_L);
  Motor_Upper_R(1, speed_Upper_R);
  Motor_Lower_R(1, speed_Lower_R);
}


void mecanumCar::Back()
{
  Motor_Upper_L(0, speed_Upper_L);
  Motor_Lower_L(0, speed_Lower_L);
  Motor_Upper_R(0, speed_Upper_R);
  Motor_Lower_R(0, speed_Lower_R);
}


void mecanumCar::Turn_Left()
{
  Motor_Upper_L(0, speed_Upper_L);
  Motor_Lower_L(0, speed_Lower_L);
  Motor_Upper_R(1, speed_Upper_R);
  Motor_Lower_R(1, speed_Lower_R);
}


void mecanumCar::Turn_Right()
{
  Motor_Upper_L(1, speed_Upper_L);
  Motor_Lower_L(1, speed_Lower_L);
  Motor_Upper_R(0, speed_Upper_R);
  Motor_Lower_R(0, speed_Lower_R);
}



void mecanumCar::L_Move()
{
  Motor_Upper_L(0, speed_Upper_L);
  Motor_Lower_L(1, speed_Lower_L);
  Motor_Upper_R(1, speed_Upper_R);
  Motor_Lower_R(0, speed_Lower_R);
}


void mecanumCar::R_Move()
{
  Motor_Upper_L(1, speed_Upper_L);
  Motor_Lower_L(0, speed_Lower_L);
  Motor_Upper_R(0, speed_Upper_R);
  Motor_Lower_R(1, speed_Lower_R);
}


void mecanumCar::LU_Move()
{
  Motor_Upper_L(0, 0);
  Motor_Lower_L(1, speed_Lower_L);
  Motor_Upper_R(1, speed_Upper_R);
  Motor_Lower_R(0, 0);
}


void mecanumCar::LD_Move()
{
  Motor_Upper_L(0, speed_Upper_L);
  Motor_Lower_L(0, 0);
  Motor_Upper_R(0, 0);
  Motor_Lower_R(0, speed_Lower_R);
}




void mecanumCar::RU_Move()
{
  Motor_Upper_L(1, speed_Upper_L);
  Motor_Lower_L(0, 0);
  Motor_Upper_R(0, 0);
  Motor_Lower_R(1, speed_Lower_R);
}


void mecanumCar::RD_Move()
{
  Motor_Upper_L(0, 0);
  Motor_Lower_L(0, speed_Lower_L);
  Motor_Upper_R(0, speed_Upper_R);
  Motor_Lower_R(0, 0);
}



void mecanumCar::drift_left()
{
  Motor_Upper_L(0, 0);
  Motor_Lower_L(0, speed_Lower_L);
  Motor_Upper_R(0, 0);
  Motor_Lower_R(1, speed_Lower_R);
}


void mecanumCar::drift_right()
{
  Motor_Upper_L(0, 0);
  Motor_Lower_L(1, speed_Lower_L);
  Motor_Upper_R(0, 0);
  Motor_Lower_R(0, speed_Lower_R);
}




void mecanumCar::Motor_Upper_L(bool stateL, int left1)
{
  if (stateL) {
    PWM_OUT(3, 0);
    PWM_OUT(4, left1);
  } else {
    PWM_OUT(3, left1);
    PWM_OUT(4, 0);
  }
}



void mecanumCar::Motor_Lower_L(bool stateL, int left1)
{
  if (stateL) {
    PWM_OUT(7, 0);
    PWM_OUT(8, left1);
  } else {
    PWM_OUT(7, left1);
    PWM_OUT(8, 0);
  }
}



void mecanumCar::Motor_Upper_R(bool stateR, int right1)
{
  if (stateR) {
    PWM_OUT(1, 0);
    PWM_OUT(2, right1);
  } else {
    PWM_OUT(1, right1);
    PWM_OUT(2, 0);
  }
}


void mecanumCar::Motor_Lower_R(bool stateR, int right1)
{
  if (stateR) {
    PWM_OUT(5, 0);
    PWM_OUT(6, right1);
  } else {
    PWM_OUT(5, right1);
    PWM_OUT(6, 0);
  }
}


void mecanumCar::right_led(bool onoff)
{
  digitalWrite_P55(onoff);
}


void mecanumCar::left_led(bool onoff)
{
  digitalWrite_P54(onoff);
}



/**
  设置P55的数字信号输出
  val为写入的数字信号，1则输出高，0则输出低
**/
void mecanumCar::digitalWrite_P55(bool val)
{
  Writebyte(0x0A, val);
}


/**
  设置P54的数字信号输出
  val为写入的数字信号，1则输出高，0则输出低
**/
void mecanumCar::digitalWrite_P54(bool val)
{
  Writebyte(0x09, val);
}


/**
  PWM output function
  ch is the PWM output channel 1~8, val is the written pwm value 0~255
**/
void mecanumCar::PWM_OUT(uint8_t ch, uint8_t pwm) 
{
  Writebyte(ch, pwm);
}

/****指定地址写入1个字节数据  dat数据 addr寄存器地址*****/
void mecanumCar::Writebyte(uint8_t addr, uint8_t dat) 
{
  IIC_Start();
  IIC_SendByte(0x30<<1);
  IIC_RecvACK();
  IIC_SendByte(addr);
  IIC_RecvACK();
  IIC_SendByte(dat);
  IIC_RecvACK();
  IIC_Stop();
}

/***I2C起始信号***/
void mecanumCar::IIC_Start() {
  digitalWrite(SDA, HIGH);
  delayMicroseconds(1);
  digitalWrite(SCL, HIGH); //拉高时钟线
  delayMicroseconds(1);  //延时2us
  digitalWrite(SDA, LOW);
  delayMicroseconds(1);
  digitalWrite(SCL, LOW);
  delayMicroseconds(1);
}

/*****I2C停止信号******/
void mecanumCar::IIC_Stop() {
  digitalWrite(SCL, LOW);  //拉低数据线
  delayMicroseconds(1);
  digitalWrite(SDA, LOW);  //拉低时钟线
  delayMicroseconds(1);    //延时us
  digitalWrite(SCL, HIGH);
  delayMicroseconds(1);
  digitalWrite(SDA, HIGH);
  delayMicroseconds(1);
}

/**************************************
  发送应答信号
  入口参数:ack (0:ACK 1:NAK)
**************************************/
void mecanumCar::IIC_SendACK(bool ack) {
  digitalWrite(SDA, ack);   //写应答信号
  delayMicroseconds(1);
  digitalWrite(SCL, HIGH);  //拉高时钟线，等待读取应答信号
  delayMicroseconds(1);  //延时
  digitalWrite(SCL, LOW);   //拉低时钟线
  delayMicroseconds(1);   //延时
}

/**************************************
  接收应答信号
**************************************/
bool mecanumCar::IIC_RecvACK() {
  bool CY;
  digitalWrite(SCL, LOW);
  //digitalWrite(SDA, HIGH); //释放总线，<这里不拉高波形更好。。。>
  pinMode(SDA, INPUT);  //这里要读取信号，所以数据线设置为INPUT
  digitalWrite(SCL, HIGH);
  delayMicroseconds(1);
  CY = digitalRead(SDA);
  digitalWrite(SCL, LOW);
  pinMode(SDA, OUTPUT);//必须要重新设置输出模式
  return CY;
}

/**************************************
  向IIC总线发送一个字节数据
**************************************/
void mecanumCar::IIC_SendByte(unsigned char dat) { //dat是要发送的一个字节的数据
  uint8_t i;
  for (i = 0; i < 8; i++) {  //高位开始传输
    digitalWrite(SCL, LOW);
    delayMicroseconds(1);
    if (0x80 & dat) digitalWrite(SDA, HIGH);  //置1
    else digitalWrite(SDA, LOW);  //置0
    dat <<= 1;
    delayMicroseconds(1);  //延时
    digitalWrite(SCL, HIGH);  //拉高时钟线 读取数据
    delayMicroseconds(1);
  }
}

/**************************************
  在IIC总线接收一个字节数据
**************************************/
unsigned char mecanumCar::IIC_RecvByte() {
  digitalWrite(SDA, HIGH); //释放总线
  uint8_t i;
  uint8_t dat = 0;    //dat是存放接收到的一个字节的数据
  pinMode(SDA, INPUT);  //这里要读取信号，所以数据线设置为INPUT
  for (i = 0; i < 8; i++) {
    digitalWrite(SCL, HIGH);
    delayMicroseconds(1);
    dat <<= 1;
    if (digitalRead(SDA)) dat++;
    delayMicroseconds(1);
    digitalWrite(SCL, LOW);
    delayMicroseconds(1);
  }
  pinMode(SDA, OUTPUT);
  return dat;
}

How Could I use the four IIC Blockes of MicroBlocks to communicate with the STC microcontroller?

Thanks.

[John Maloney]

The code you sent (Writebyte() and the functions it calls) appears to implement the low-level I2C protocol by changing digital pins. That may not be necessary, assuming that the STC51 implements the standard I2C protocol.

I would start by implementing WriteByte like this:

It looks like address 1-8 are the PWM values for the motors, so I would try:

and see if the first motor turns on. If so, you'll know you are on the right track. If it doesn't work, you could try reducing the I2C clock to 100 kHz (vs. the MicroBlocks default of 400 kHz) with this block:

Be sure to use to the correct I2C pins for the microcontroller that is running MicroBlocks. Also be sure that the I2C lines have pullup resistors (they are probably builtinto the remote control car).

Good luck!

[Tom Ming]

Thanks for quick reply.

what’s the definition of set i2c clock speed 100000 ? I could not find it on Comm Blocks, Thanks.

‌

[Tom Ming]

Oh, I found it on sensor Primitive. Thanks!

[Tom Ming]

@John Maloney

It works.Thanks for your help.

BR

‌

[Tom Ming]

I works.Thanks for your help.

[John Maloney]

Great that it works! Congratulations!

You might try omitting the clock speed block; it may work. Most commercial I2C devices support 400 kHz "fast" mode so that's what MicroBlocks uses as the default. But sometimes hand-written controllers need to run at the standard mode 100 kHz clock rate.

[Tom Ming]

OK. I will have a try. Thanks again.